Both the brain and the pituitary gland have been known to contain mitogenic factors for cultured cells; however, until 1974, it was unclear what their relationship was with classical pituitary hormones, such as TSH, LH, FSH, GH and ACTH. In 1974, the identification in the pituitary gland of a growth factor called fibroblast growth factor (FGF) was reported which was shown to be distinct from pituitary hormones, Gospodarowicz, D. Nature, 249, 123-127 (1974). This growth factor is now known to have a MW of 16,415, is basic (a pI of 9.6), and is a potent mitogen for either normal diploid fibroblasts or established cell lines. Purification of an acidic brain FGF is described in U.S. Pat. Nos. 4,444,760 (Apr. 24, 1984). Later studies confirmed that, in addition to fibroblasts, FGF is also mitogenic for a wide variety of normal diploid mesoderm-derived and neural crest-derived cells, including granulocytes, adrenal cortical cells, chondrocytes, myoblasts, corneal and vascular endothelial cells from either bovine or human origin, vascular smooth muscle cells, and lens epithelial cells. FGF was also shown to substitute for platelet-derived growth factor in its ability to support the proliferation of fibroblasts exposed to plasma-supplemented medium. Consistent with its ability to stimulate the proliferation of bovine and vascular endothelial cells, FGF has a similar activity in vivo on capillary endothelial cells; therefore, FGF is considered an angiogenic factor.
Above-identified U.S. application, Ser. No. 586,518, the teachings of which are incorporated herein by reference, describes a purification of mammalian fibroblast growth factor (FGF) using reverse-phase high performance liquid chromatography (RP-HPLC). Above-identified U.S. application, Ser. No. 670,160, the teachings of which are incorporated herein by reference, describes a purification of mammalian FGF by heparin-Sepharose affinity chromatography.
Although the above-identified patent applications describe methods of purifying FGF from mammalian tissue, such as bovine pituitary tissue, these procedures may be difficult to scale up to large scale production.
The present invention provides pure FGF which may be produced by synthetic methods, and if so produced should substantially enhance the availability of mammalian FGF.